For the chassis of electronic devices such as mobile phones, in consideration of a variety of factors such as decorativeness, scratch resistance, workability, and cost, an appropriate material selected from resins, metals, and other materials is used. In recent years, an attempt has been made regarding the use of glass, which was not used in the past, as a material for chassis (Patent Document 1). According to Patent Document 1, in electronic devices such as mobile phones, when the chassis main body is formed of glass, it is possible to exhibit a unique transparent decoration effect.
An electronic device includes a display device such as a liquid crystal panel on the outer surface of the device. For the display device, there is a tendency to high definition and high brightness and, accordingly, for backlights serving as a light source as well, there is a tendency to high brightness. Light from a light source is not only radiated toward the display device side but is also, in some cases, reflected in the inside of the device multiple times so as to arrive at the inner surface of the chassis covering the device.
Even for organic EL (Electro-Luminescence) displays requiring no light source, similarly, there is a concern of the leakage of light coming from a light-emitting element. When metal is used as a chassis material, no problem is caused; however, in the case of using the transparent glass, there is a concern that light from the light source may pass through the chassis and be sensed outside the device. Therefore, when glass is used for the chassis, a method for forming a coated film to impart shielding properties against visible light (hereinafter, simply referred to as shielding properties) to the glass has been used.
In order to form a coated film having sufficient shielding properties on the inner surface (facing the device) of the glass, it is necessary to form a thick coated film or form a film made up of a plurality of layers, which increases the number of steps and the cost.
In addition, in the case in which the coated film is not uniformly formed, there is a concern that the appearance of the device is impaired since light passes through only places having a thin coated film and the chassis is locally sensed to be bright. For example, for a recessed chassis, it is necessary to form a uniform film on the entire surface of the recessed surface. However, a step for uniformly forming a coated film having sufficient shielding properties on the recessed surface is complicated and thus causes an increase of the cost.